Tuesday, July 29, 2008

Knee-protecting shoes

Osteoarthritis of the knee is a common condition that can be relieved by reducing the force experienced by the knee when a person walks.

Since these forces are transmitted through the foot, they can be influenced by footwear. Walking barefoot significantly decreases one of the key force-related effects on the knee by 12% compared to walking with common walking shoes, say Roy Lidtke and Najia Shakoor at the Rush University Medical Center in Chicago.

Funded by the US National Institutes of Health, these researchers have designed a shoe with a number of separate zones that flex as it bends, allowing weight to be transferred just as in bare feet and reducing the peak load experienced by the knee.

The result is a shoe design that should help to reduce wear and tear on the knees and also to help reduce the pain of osteoarthritis in the knees.

Friday, July 25, 2008

Inhaler can target left or right lung

An increasingly common way of treating cancers, AIDs and diabetes, not to mention asthma, is by inhaling a drug in aerosol form.

But inhalers are notoriously inefficient. At best they deliver 20% of their load into the lungs. At worst, they deliver less than 5%. The rest gets left in the mouth and throat, or gets blown back out into the air, particularly if the user's intake of breath is not well synchronised with the aerosol jet.

With some drugs costing more than their weight in gold, that is an expensive waste.

So Clement Kleinstreuer, a mechanical engineer at North Carolina State University in Raleigh, has developed a computer-controlled inhaler that measures air flow around its nozzle to determine the best moment to release a powdered drug to achieve maximum penetration into the lungs.

Kleinstreuer even claims to be able to target specific areas of the lungs with a drug. This is done by injecting powder into different parts of the airflow, aiming the drug towards the right or left lung or even areas within each lung. That could make inhalers far more efficient at targeting the conditions they are designed to treat.

Wednesday, July 23, 2008

Lorry drivers' power generator

Lorry drivers often have to run their engines when their vehicle is at rest to power what is known as their "hotel load" – the air-conditioning unit, the radio or TV, and other auxiliary equipment.

A driver may sometimes run their hotel load for as long as five hours per day or night. But the practice is noisy, polluting, wasteful (idling is a particularly fuel inefficient), and wears the engine.

So Richard Stobart at the University of Sussex in southeast England has designed an alternative power source.

His answer is to use exhaust gases while the engine is running normally to heat a tank of pressurised water to its critical temperature – just below boiling.

When the engine is turned off, this water can then be harnessed by allowing it to expand into steam through a turbine that generates electricity. Or it can provide heat directly to the cabin when the weather is cold.

Monday, July 21, 2008

Human organ-on-a-chip

Drug testing is an expensive business because of the huge cost of carrying out tests on animals and humans. This is why various researchers have been trying to develop "silicon guinea pigs" – microchips carved with wells and interconnecting grooves designed to mimic the structure of human organs.

The idea is that cells from a real organ, such as the liver, would be grown in these structures and then used to test the toxicity of various drugs.

But Wei Li, a mechanical engineer at the University of Washington in Seattle, says the trouble with silicon guinea pigs is that they are only two dimensional and may not allow the grown cells to realistically mimic a human organ.

To counter this drawback, Li has designed a three-dimensional guinea pig chip made of polymer. The chip contains various cavities connected by tubes that mimic the 3D structure of human tissue. Li believes the chip is a more realistic environment in which to grow human tissue and should provide a better environment for test new drugs.

Friday, July 18, 2008

Artificial whiskers

Animals use hair as an extraordinarily sensitive way to probe their environment. By contrast, the sensors designed by scientists tend to use power hungry parameters such as temperature and resistance to measure similar factors.

But Chang Liu at the University of Illinois in Urbana-Champaign, US, and colleagues have developed polymer hairs sitting on silicon microchips that do a similar job. These hairs are more robust than silicon sensors and could be used as a sensitive and cheap way to monitor nearby objects and the flow of air or water.

The design consists of an artificial hair deposited on a silicon substrate and connected to it by a flexible hinge. When a magnetic field is applied, the hinge bends, causing the hairs to stand up straight. For protection, the hairs can be embedded in a polymer skin.

Movement of a hair can be monitored as it bends - a process that changes its resistance - creating an artificial hair cell that can "sense" its environment.

The idea appears to work well in prototypes. Liu says that the silicon hairs could cover aerodynamic models in wind tunnels giving immediate feedback on wind speed.

Rising and lowering the hairs could even modify the airflow and the amount of lift produced by the model. Perhaps that explains why NASA - who funded the work - is so interested.

Wednesday, July 16, 2008

Hurricane prediction

During the summer and autumn, a large body of warm water with a surface temperature of more than 28 °C appears in the Gulf of Mexico.

This warm water is known to provide the energy that allows hurricanes to build into hugely damaging storms. However, some hurricanes are much more powerful than others and Alexander Soloviev at Nova Southeastern University in Florida, US, thinks he knows why.

The key, he says, is the rate at which warm water drains from this hotter area into a cooler part of the north Atlantic, a flow known as a "warm water exhaust current".

At certain times, the current cannot remove heat fast enough from the gulf and the heat energy builds up, creating conditions that are particularly favourable for intense hurricane formation.

Soloviev says that by trawling through past oceanographic records, he has found that internal waves build up in the exhaust current when the flow cannot remove heat fast enough. These are detectable using an array of oceanographic pressure sensors.

The period of these waves is usually measured in days, but when this period drops to about 10 hours, dangerous conditions are building. Soloviev says that by looking out for these waves, he can predict when the most dangerous hurricanes are most likely to form and so warn the authorities to take protective action.

Monday, July 14, 2008

Smart stethoscope

Coronary artery disease is a major cause of death in industrialised nations. Approximately 13 million people in the United States alone are estimated to suffer from it.

The condition is caused by the thickening and hardening of arterial walls as substances such as fat, cholesterol and calcium, accumulate in the arteries. This causes them to become narrow, potentially leading to chest pain, heart attacks and sudden death.

There is an urgent need for a non-invasive way to detect these conditions, says John Semmlow at the University of Medicine and Dentistry of New Jersey, who has developed a smart stethoscope connected to a computer that could do the trick.

His idea is based on the principle that blood flow through restricted arteries sounds different to the flow through healthy vessels. The device listens to the noise that the blood makes as it flows though the heart, filters out any unwanted background noise and then looks for the telltale signs that artery disease is present.

Friday, July 11, 2008

Dirty bomb dose detector

So-called "dirty bombs" are designed to spread significant amounts of radioactive dust and debris throughout a populated area.

But working out what kind of radiation dose the local people have received is a difficult business, not least because this may involve testing tens or hundreds of thousands of them.

That is a problem because current techniques for estimating radiation dosage rely on blood samples that can only be taken by trained individuals. This severely limits the rate at which people can be tested. The tests look for changes in the metabolites generated by cells when they are exposed to radiation and which then end up in the blood.

However, Albert Fornace at Georgetown University in Washington, DC, US, funded by the US government, says that these metabolites also turn up in saliva and urine, but not in high enough concentrations for current testing equipment to detect.

However, Fornace and his team say the required sensitivity is possible using a new generation of lab-on-a-chip technologies that he is developing. Because they rely on easily obtainable saliva and urine samples, the machines should allow a much higher throughput of tests in an emergency.

Thursday, July 10, 2008

Eco-friendly tattoo removals

Lasers are used routinely in plastic surgery to remove tattoos and other skin blemishes. But surgeons have to be careful that the radiation doesn't heat the skin above 70 °C, the threshold above which cell damage causes scarring.

To prevent this, they usually spray the skin with a cold, volatile liquid such as tetrafluoroethane which reduces the temperature of the skin to around 3 °C as it evaporates. Precooling can increase the amount of heating the skin can safely accept by a factor of two, allowing the surgery to proceed more quickly.

Tetrafluoroethane is currently the liquid of choice because it does not damage the ozone layer, but recent work has shown that the chemical is a greenhouse gas many times more potent than carbon dioxide.

John Stuart Nelson Medical Director at the Beckman Laser Institute of the University of California, Irvine, US, says that laser surgeons can ease their eco consciences by switching to a carbon-dioxide spray that does the job just as well, while reducing the impact on the environment.

His idea is to store liquid CO2 under pressure and spray it onto the skin undergoing laser treatment. This produces a fine mist of solid CO2 particles – dry ice – that cool the skin before sublimating into gas.

Tuesday, July 08, 2008

Jet turbine armour

When operating in the desert, the turbines in jet engines and helicopter engines are continually blasted by sand. This eventually causes the leading edge of each aerofoil on the turbine to fold over on itself forming a bur and reducing the efficiency and lifetime of the engine.

The American engine maker General Electric, funded by the US Office of Naval Research, has come up with an anti-erosion coating consisting of alternating layers of an extremely hard ceramic such as tantalum carbide and a metal such as niobium, which can absorb the stresses that might otherwise cause the ceramic to crack.

The company says this should prevent the formation of burs, making turbines destined for the desert more efficient and longer lasting.

Friday, July 04, 2008

Jet-engine silencer

Aircraft noise is serious problem for the aviation industry, particularly during take off and landing near urban areas. Jet engines are a major source of that noise.

Now, though, Dimitri Papamoschou at the University of California, Irvine, US, says it is possible to quieten a jet engine by separating its exhaust into high and low speed flows.

He says that most of an engine's noise comes from turbulence in the fastest-flowing air. By separating the air into two channels of different speeds, he says the noise can be directed upwards, away from the ground and its inhabitants.

In simulations, funded by NASA, Papamoschou found that this technique can reduce the amount of noise heading towards the ground by more than 6 decibels.

This is a significant amount given that decibels are a logarithmic scale, so that every drop of 3 decibels is equivalent to a halving of power. A "silenced" engine would produce about a quarter of the acoustic energy of a conventional one and be significantly quieter.

Thursday, July 03, 2008

Wireless robot sub recharger

But powering them is problematic. Having the robots feed on plankton is one idea, but simply having them recharge underwater without human input would cut the costs of attending boats and crew, and is a more near-term solution.

In principle, a docking AUV could recharge its batteries, download the data it has collected during its mission, and upload new mission plans all at once.

But conventional electrical contacts are fraught with problems underwater, says a team funded by the Office of Naval Research in Arlington, Virginia, US. Saltwater can corrode metal contacts, and growths of algae and other marine life can appear on exposed metal in just 10 days.

So Robert Coulson and colleagues have designed a wireless energy transfer system – a strong magnetic field made by the docking station induces a current in a part of the AUV to charge its batteries. The dock could be installed in a remote area costly to reach by ship.

Noise-cancelling MRI scanner

Magnetic-resonance imaging machines produce amazingly detailed images of our bodies, but at the cost of potentially damaging levels of noise.

Adults and children can be protected using ear defenders, but some experts are concerned that the hearing of unborn children could be permanently damaged by such scans.

MRI machines contain two types of magnet. Giant superconducting coils create the powerful, constant field that envelops the patient, while smaller a set of smaller gradient coils produce a rapidly varying field to pinpoint and image a slice of the body.

These secondary coils vibrate rapidly as the magnetic fields they generate switch back and forth, making a distinctive hammering sound.

Electronics company Philips says the noise can be reduced by making the main magnets vibrate in the opposite direction, cancelling out the vibration. That should make MRI machines quieter for everyone, as well as safer for unborn children.